The API 6D fully welded trunnion ball valve for buried installation represents a mature, field‑proven technical solution responding to the core challenges of long‑distance natural‑gas transmission infrastructure: high continuous operating pressure, underground environmental corrosion, limited site access, and zero‑tolerance for hazardous gas leakage. Its fully‑welded monolithic body eliminates gasket‑equipped bolted joints that are the single‑largest source of underground‑valve external‑leakage incidents.








